Process for dyeing products of copoly-



United States Patent Oflice 2,900,217 Patented Aug. 18, 1959 PROCESS FOR DYEING PRODUCTS OF COPOLY- MERS F ACRYLONITRILE Hendrik Waning, Nimeguen, Netherlands, assignor to Naamlooze Vennootschap Kunstzijdespinnerij Nyma, Nimeguen, Netherlands, a Dutch company No Drawing. Application July 6, 1955 Serial No. 520,355

Claims priority, application Netherlands July 16, 1954 1 Claim. (Cl. 8-42) The invention relates to a process for dyeing products of copolymers of acrylonitrile, particularly those which contain more than 80% of acrylonitrile. The properties of such products are in general very similar to those of pure polyacrylonitrile: they excel because of their great strength, resistance to chemical attack and the action of light. They have, however, the drawback that they are difficult to dissolve-special solvents, for instance dimethyl formamide are necessaryand that they are very difli cult to dye.

Irgalan-," Neolan-, Cibalan-, and Palatin-echtdyestuffs are known as acid wool dyestuffs which contain a complex bound metal, such as chromium or cobalt. Those dyestuffs do not dye polyacrylonitrile and the above-mentioned copolymers of acrylonitrile if one proceeds according to the procedure usual for wool, in which one acidifies the dye bath with acetic acid or (NH SO and dyes at about 100 C.

Neolan and Palatin-echt" are trademarks for 1-1 monoazo chromium dyes, existing under one or more of the following Colour Index numbers:

Neolan" Palatin-echt" Irgalan and Cibalan" are trademarks for metalliferous azo dyes without sulfonic acid groups and having two molecules of dyestuff per molecule of metal, these dyes being used in a substantially neutral dye bath and existing under one or more of the following Colour Index prototype numbers:

Irga1an" Oibalan" French Patent No. 954,752 describes the dyeing of textile products of a copolymer of acrylonitrile and a vinyl halide, in which a temperature above 100 C. is used and in which a salt such as sodium phosphate is present. This patent relates to copolymers which are easily dissolved in ordinary solvents, such as acetone and which-parallel with their better solubility--absorb dyestufl's more readily. The dyeing process given in this patent, in so far as it relates to normal acid dyestuffs, is, therefore, entirely unsuitable for dyeing the difiicultly soluble copolymers. That those copolymers can be dyed by choosing the temperature above 100 C. and in the presence of a salt, provided one makes use of acid dyestuffs which contain a complex bound metal, could not at all be expected on account of the knowledge provided by the cited French patent.

The invention is elucidated by the following examples.

Example I 400 grams of yarn of a copolymer of acrylonitrile (95%) and methyl methacrylate were dyed for one hour at 125 C. in a bath having the following composition:

7250 cm. of water, 10 grams of Irgalan Red 3 G.

In this way a very pale color was obtained.

When the same experiment was repeated, in which grams of Na SO were added to the bath, a dark red yarn was obtained. The same improvement in the dyeing quality by the Na SO addition was established with l'rgalan Gray BL and Irgalan Brown 3 BL.

Similar experiments in which NaCl or NaCNS was used instead of Na SO and in which a copolymer of acrylonitrile and of methyl acrylate or a copolymer of acrylonitrile (95%) and of vinyl acetate was dyed, proved the same favorable influence of the salt addition.

On repetition of all the above mentioned experiments, in which in the presence of a salt a dye temperature of C. was chosen, no dyeing was obtained or a very pale dyeing was obtained.

Example II 400 grams of yarn of a copolymer of acrylonitrile (95 and of methyl acrylate were dyed for one hour at C. in a bath having the following composition:

7250 cm. of water, 10 grams of Cibalan Yellow GRL, 75 grams of NaCl.

In this manner a clear yellow yarn was obtained.

If experiment was repeated, in which no salt was added and/or the dye temperature of 100 C. was chosen, a pale yarn was obtained.

Similar experiments with the same dyestuff, in which instead of yarn of the above mentioned copolymer yarn of a copolymer of acryonitrile (95%) and of vinyl acetate or a copolymer of acrylonitrile (95%) and of methyl methacrylate was dyed and in which instead of 75 grams of NaCl one of the other salts mentioned in Example I was used, proved the same favorable influence of the salt addition and the dye temperature of 125 C.

The invention is not concerned with those copolymers of acrylonitrile, for instance a copolymer of acrylonitrile and of vinyl pyridine, in which basic groups are introduced into the macromolecule which render it possible to dye the copolymer with acid wool dyestuffs by means of the basic group with the dyeing procedure usual for W001.

What is claimed is:

Process for dyeing a copolymer of acrylonitrile and an olefinic compound selected from the group consisting 3 4 of methyl acrylate, methyl methacrylate and vinyl acetate, References Cited in the file of this patent which copolymer contains at least 80% of acrylonitrile, UNITED STATES PATENTS which comprises the step of treating the copolymer in a dye bath containing a metallized azo dyestuff selected 2543316 Feud 1951 from the group consisting of 1-1 monoazo chromium 6 complex dyes and metalliferous azo dyes without sul- FOREIGN PATENTS fonic acid groups having two molecules of dyestufi per 923,442 France 17, 1947 molecule of metal and used in a substantially neutral dye bath, and an inorganic water-soluble alkali salt at OTHER REFERENCES atemperature above 100 C. 10 Am. Dyestuff Reporter for Jan. 22, 1951, p. P51. 

